Food and feeding habits of the king crab Paralithodes camtschatica near Kodiak Island,Alaska

Stomach contents from 809 king crabs, Paralithodes camtschatica (Tilesius), from 6 areas near Kodiak Island, Alaska, and 9 sampling periods (1978–1979) were exammed quantitatively; 713 (88%) contained food. Mollusca (mainly the bivalves Nuculana spp., Nucula tenuis, and Macoma spp.) and Crustacea (mainly barnacles) were the dominant food groups in terms of percentage wet weight and frequency of occurrence; fishes were the next most important group of prey. No significant differences in feeding between sexes occurred; however, significant differences were apparent in the quantity of food consumed from different sampling periods, areas, depths, size groups, and crab molt-classes. Consumption was greater in spring and summer and in offshore locations at depths of 126 to 150 m. In addition, king crabs <140 mm carapace length (CL) consumed more food than crabs 140 mm CL. Adult, newshell (individuals that molted during the last molting period) females greater than 95 mm CL, and newshell males greater than 100 mm CL, each contained more food than did juvenile, newshell females <120 mm CL.Contribution No. 449, Institute of Marine Science, University of Alaska, Fairbanks, Alaska 99701, USA     

Feeding,growth, and survival of Engraulis mordax larvae reared in the laboratory

Methods are described for the successful rearing of northern anchovy larvae (Engraulis mordax Girard) on cultured foods. Larvae were fed successively on the unarmored dinoflagellate Gymnodinium splendens, the veliger of the gastropod Bulla gouldiana, and nauplii of the brine shrimp Artemia salina. Rearing containers ranging in capacity from 4.5 to 510 l were tested; the smaller ones were found to be most useful for laboratory experimentation. Irreversible starvation occurred when E. mordax were denied food for more than 1.5 days after yolk absorption. Growth rates of larval anchovies fed different diets were compared. Larvae fed G. splendens grew for 1 week at the same rate as animals fed wild plankton, but did not maintain this rate. Laboratory survival of E. mordax larvae on a diet of G. splendens alone, did not differ significantly when veligers supplemented the diet. However, when G. splendens and veligers were fed simultaneously to E. mordax larvae, growth rate was greatly improved, although still not matching the growth attained on a diet of wild plankton. Length (L) versus weight (W) analyses were made for all larvae at all diets. The results showed that weight could be calculated most accurately from length by the relationship log W=3.3237 log L-3.8205, regardless of diet.     

Biological interactions and environmental effects in the economics of pest control

The problem of pest control is tackled in a context of an ecosystem that consists of prey-predator populations with human interaction through pesticide application. The control, aimed at reducing pest damage, results in two undesirable external effects: reduction of beneficial predator population and environmental contamination. The untapped natural equilibrium is compared with equilibrium resulting from decentralized and centralized economic decision making. It is shown that, under certain conditions, myopic decision rules increase rather than decrease the pest damage. The “user cost” (or benefit) is shown to be crucial in determining the optimal centralized policy, and its relations to the various components of the system are analyzed. The components of the user cost are analyzed to determine the level of taxes or subsidies that will yield the optimal policy.     

陕西民俗文化旅游资源的保护与开发

陕西民俗文化旅游资源丰富,具有较高的社会价值和旅游价值,但由于政府部门的疏于重视和广大民众认识的浅薄,导致陕西民俗文化旅游资源受到严重的破坏,同时也造成不良风气的大量出现,使这些价值未能得以发挥.针对这一现状,以全国民俗文化的保护和开发为参照,结合陕西民俗文化旅游资源的自身特点,从保护和发展两个方面涉及的具体问题为出发点,就具体的问题提出了具体的建议,希望以此引起各方重视.参5.     

Qualitative structure residue relationship analysis in the determination of the maximum residue limit of veterinary drugs

Aim of the present study was an attempt to find a correlation between physicochemical structure of veterinary drugs and the maximum residue limit (MRL) for muscle tissue of food producing animals. Direct correlation and analysis in quintile groups for 52 physicochemical parameters were performed. An internal validation using leave-one-out cross-validation was performed. In the quintile groups, there were 11 arithmetic expressions created for the limited group of individual parameters (13 from 52 analyzed), which showed a significant linear or quadratic correlation between the number of quintile group and the mean value of MRL within the quintile. The results obtained suggest that there is no direct correlation between individual physicochemical parameters and MRL value in muscle tissue; however, such correlation can be determined for arithmetic expressions created on the basis of several physicochemical parameters, using quintile group analysis.     

Growth and disease response of soybeans from early maturity groups to ozone and Fusarium oxysporum

The single and combined effects of ozone (O(3)) and Fusarium oxysporum on growth and disease expression of soybean genotypes differing in foliar sensitivity to O(3) were studied in the greenhouse. O(3) had no effect on root and hypocotyl rot severity of PI 153.283 (O(3)-sensitive, S) or PI 189.907 (O(3)-tolerant, T) maturity group I soybean lines. Plants of both genotypes infected with F. oxysporum and exposed to O(3) had greater reductions in relative growth rate (RGR), net assimilation rate (NAR), and had more stippled leaves per plant than Fusarium-free plants exposed to O(3). O(3) alone had a greater impact on shoot dry weight, RGR, and NAR of PI 153.283 (S) than of PI 189.907 (T). O(3) alone reduced shoot and root dry weights primarily through a depression in NAR and less through reduced leaf area. F. oxysporum alone reduced root dry weight at 35 days; however, infected plants responded with increases in root dry weight from 49 to 63 days. Similarly, F. oxysporum alone lowered early RGR but subsequent RGR decline was less rapid while NAR remained high, particularly during later sampling intervals. Infection by F. oxysporum that causes root and hypocotyl rot increased soybean sensitivity to O(3) by prolonging active vegetative growth.     

Differences in the electroantennal responses of apple- and hawthorn-infesting races of Rhagoletis pomonella to host fruit volatile compounds

Summary. Domestic apple (Malus pumila)- and hawthorn (Crataegus sp.)-infesting races of Rhagoletis pomonella, Walsh (Diptera: Tephritidae) provide an excellent model to examine the role that host plant specificity plays during sympatric speciation (i.e., divergence in the absence of geographic isolation). Previous work has shown that these races differ in their propensities to accept apple and hawthorn fruits in behavioral choice assays, and that this discrimination translates into "host fidelity" in the field (i.e., apple flies tend to mate on and oviposit into apples and hawthorn flies on hawthorns). ?We present the results of a study examining possible physiological factors contributing to host choice differences in R. pomonella. We tested whether apple and hawthorn flies differ in their electroantennogram (EAG) responses to biologically relevant volatile compounds emitted from apples and hawthorns. Significant differences were found in the relative EAG responses of apple and hawthorn flies to host fruit compounds at five of six paired study sites across the eastern United States. The geographic pattern of EAG variation was complex, however, with local populations of apple and hawthorn flies tending to be more similar to one another than to flies of the same race at distant sites. This pattern was largely due to EAG responses for several compounds showing longitudinal or latitudinal clines, the latitudinal clines being similar to those observed for allozyme loci in the host races. We also found evidence for sex-related differences, as males tended to have higher mean EAG responses to compounds than females. Host-associated differences were therefore nested within geographic and sex-related differentiation in R. pomonella.?Further behavioral studies are needed to distinguish whether the EAG differences are responsible for, as opposed to being a consequence of, host-plant fidelity and adaptation. Crosses are also required to establish a genetic basis for the EAG responses, although we did find significant correlations between EAG scores for several compounds and the allozymes NADH-Diaphorase-2 and Hydroxyacid dehydrogenase at one of the study sites. Questions therefore remain concerning the evolutionary significance of the EAG response differences between apple and hawthorn fly races. Nevertheless, these differences raise the possibility that antennal responses to fruit-related volatile compounds contribute to host plant discrimination in R. pomonella. Regardless, the EAG responses represent another set of traits, in addition to diapause/eclosion time phenotypes and allozyme frequencies, differing between apple and hawthorn host races of R. pomonella. Received 17 March 1998; accepted 21 September 1989.     

Conservation value of an exotic species: the case of coconuts on the Kayapo indigenous lands, south-eastern Amazonia

In a meeting between FUNAI (the Brazilian Indian National Foundation) and the Kayapo in the Kayapo village of Aukre, in October 2005, the Kayapo Indians requested support to increase the culture of coconuts (Cocos nucifera) in their lands. The introduction of exotic species is a cause of biological diversity loss throughout the world. However, this is by no means applicable to all kinds of exotic species. We argue that the culture of coconuts may actually be a useful tool for the conservation of this country’s indigenous lands, despite criticism to the contrary. It may also be useful as source for raw material for the indigenous people who are presently experiencing a population boom. For the Kayapo of south-eastern Amazonia, such a demographic explosion, coupled with their increasing dependence on money to purchase industrialized goods, tend to substantially increase the pressure on their lands, which still contain a substantial amount of well-preserved seasonally-dry Amazonian forests. We investigated the actual economic relevance of coconuts for the Kayapo by measuring human and coconut populations and found that this exotic palm is not important for the subsistence of these Indians, due to coconut scarcity, and that such importance is not forthcoming. In the Amazon, coconuts may be particularly useful for the Indians’ nutrition due to the high energetic value of the solid endosperm of the mature fruit. Therefore, given the importance of indigenous lands for the conservation of the Amazonian forests, the encouragement of subsistence coconut cultures in indigenous lands is defensible as a measure for the conservation of biodiversity.